Dick Weber, K5IU

Aug 2, 2014

Contesting and DX Antennas for Restricted Lots

by

Dick Weber, K5IU [email protected]

Dick Weber, K5IU

Aug 2, 2014

The goal of this presentation is to provide information so you can make reasonable “fact based” decisions / choices. Caution: There’s a large amount of incorrect information in books and articles - some of it unforgivable.

Forward Forward

(All above from ARRL publications)

Dick Weber, K5IU

Aug 2, 2014

Opening Comments • Assume no tower - looking at lower profile antennas either outside or attic mounted • Will cover 40-10M antennas – Antennas for 160 and 80M should be covered as a separate topic due to large difference (4-16X) in scale compared to 40-10M

• Assume space is limited - requiring antennas to be multiband – Will assess 20-10M performance of a range of antennas – Will assess 40-10M performance of a range of antennas

• Antenna options assessed at 25 and 35 ft heights using NEC2 models over average ground • All performance data shown at 20 degrees elevation. • Use information here to point you down the better/best path based on your unique circumstances • Goal is to provide information so you can make reasonable “fact based” decisions / choices

Dick Weber, K5IU

Aug 2, 2014

After CQ Magazine - February, 2013

Mike

Dick Weber, K5IU

Aug 2, 2014

Trick Question #1: Which Would You Prefer for Working DX?

Dick Weber, K5IU

Aug 2, 2014

Trick Question #2: Which Would You Prefer for Working DX?

Dick Weber, K5IU

Aug 2, 2014

Ground Reflection Effect Example

Direct Ray ang angReflected

Horizontally Polarized at 3.5 MHz

1.0

Very Good

0.8

Refl.Coef. Magnitude

Refl.Coef. Magnitude

1.0

0.6 Ave 0.4

Very Poor

0.2 0.0 0

10

20

30 40 50 60 Wave Angle (deg)

70

Ray

80

90

Vertically Polarized at 3.5 MHz Very Good

0.8 0.6

Ave

0.4 Very Poor 0.2 0.0 0

10

20

30

40

50

60

Wave Angle (deg)

70

80

90

Dick Weber, K5IU

Aug 2, 2014

20-10M Antennas - Vpol - Hpol - Comparison

Dick Weber, K5IU

Aug 2, 2014

20M Verticals • •

Elevated radial verticals, or similar constructs, offer better performance than ground mounted verticals Will evaluate three versions - bases set at 6 feet – essentially self supporting or guyed with monofilament line – assume coils and matching is lossless / use ave ground

Force 12 -Sigma Vertical Dipole

N6BT Bravo Verticals

Low Profile Amateur Radio (and others) ARRL

HF Antennas for All Locations Moxon, G6XN 1983 p121

17-18 ft

Dick Weber, K5IU

Aug 2, 2014

20M Verticals Over Average Ground Moxon / Force 12 -20M Sigma Vertical Dipole

0.0 dBI @ 20 deg el

16 ft + 6 ft = 22 ft

17.5 vert - 12 ft radials (3)

-0.2 dBI @ 20 deg el

17.5 ft + 6 ft = 23.5 ft

N6BT Bravo 20M Vertical

-0.4 dBi @ 20 deg el

24 ft + 6ft = 30 ft

Dick Weber, K5IU

Aug 2, 2014

20M Sloping and Bent Vertical-Like Antennas “FWD Dir.” -1.2 dB 25 ft

Myth

1.0 dBi

6 ft high

1.0 dBI

-12.0 dBi 20 deg Elev.

39 ft

-0.5 dBi

25 ft

0.2 dBi

0.2 dBi

6 ft high 20-0.4 degdBi Elev. 15 ft

20 deg Elev.

Dick Weber, K5IU

Aug 2, 2014

20M Vertical “T” with Elevated Feed Point • • •

By moving the maximum current point up there is a positive effect on gain Moves maximum current point away from shrubs, fence, other stuff… Do not use 1/4 wl sections for “T” wire - if you do, you cannot force currents to be near equal on legs resulting in pattern lifting and skewing

16 ft

0.5 dBi

Feed 17.5 ft

0.4 dBi

0.4 dBi 23.5 ft 0.5 dBi 20 deg Elev.

Dick Weber, K5IU

Aug 2, 2014

Multi Band Verticals on 20, 17, 15, 12, and 10M 16 ft

20M

15M

0.4 to 0.9 dBI @ 20 deg El

10M

17.5 ft 17M

12M

23.5 ft

17.5 ft vert - 12 ft radials (3)

20M

15M

-0.2 to 0.9 dBI @ 20 deg El

10M

17M

12M

17.5 ft + 6 ft = 23.5 ft

Moxon / / Force 12 Sigma

20M

15M

17M

16 ft + 6 ft = 22 ft

10M

12M

0.0 to 0.9 dBI @ 20 deg El

Dick Weber, K5IU

Aug 2, 2014

43 Ft Vertical Ground Mounted MFJ -2990 / Hy-Gain 6160

DX Eng 80VA-3

• 43 ft vertical exceeds 35 ft limitation - shown for reference / information • Would be susceptible to probable interaction with ground level obstructions • For 20-10M there are other antennas that will perform better that meet height restriction of 35 ft • There are antennas at 25 ft that will be significantly better

80M

20M -0.8

40M

30M

0.7

0.0

-1.3

10M

12M

17M

15M

-1.4

-0.5

Band Gain (dBi)

80 -1.3

0.6

40 -0.8

30 0.0

20 0.7

-6.4

17 -1.4

15 -0.5

12 10 0.6 -6.4

Dick Weber, K5IU

Aug 2, 2014

20M 1/2 Wave Sloping Dipole as a Multiband Antenna 25 ft

Myth

15M

10M

20M

“FWD Dir.” 6 ft high

17M

12M

39 ft

• Peak of pattern is near broadside to wire • “Null” is to rear of wire slant • “Minimum is toward sloping front of wire i.e. “ Forward” (...Myth thing again...)

• Consider pointing “Broadside” to a favored direction / option to move lower end manually to move the peak of beam (or move null) • Or have two of these pointed in different directions • A viable “set-up” from omni antennas - with minimal impact to implement Verticals From Prior Slide

Dick Weber, K5IU

Aug 2, 2014

20M 1/4 Sloper as a Multiband Antenna (No Grounded Leg) 25ft

“FWD Dir.”

15M

20M

10M

“FWD Dir.” Not Tower / Not Grounded

17M

12M

• Peak of pattern is generally near broadside to wires • Null and minimum move around a bit • Vertical wire is neither a tower nor grounded at lower end.

• Consider pointing to a favored direction / option to move lower end manually to move the peak of beam (or move null) • Or have two of these pointed in different directions • A viable “set-up” from omni antennas - with minimal impact to implement Verticals From Prior Slide

Dick Weber, K5IU

Aug 2, 2014

20-10M Multiband Horizontal Antennas

Dick Weber, K5IU

Aug 2, 2014

20M 1/2 wl Inverted Vee and Dipole at 25 and 35 Ft - Used Multiband • 20-10M multiband inverted vee at 25 and 35 feet with 120 deg included angle • Dipole could be rotated with a TV rotator / hand • All plots at 20 deg elevation 34-35 Ft

34-35 Ft

25 Ft High 20, 15, 10M

17 and 12 M

35 Ft High 20, 15, 10M

17 and 12 M

25 Ft High

35 Ft High

20, 15, 10M

20, 15, 10M

17 and 12M

17 and 12M

Dick Weber, K5IU

Aug 2, 2014

20M 1/2 wl, Bent, Horizontal Dipole at 25 and 35 Ft - Used Multiband • 20-10M multiband, bent dipole - bent 90 degrees • Might be a good choice to put in an attic space • Maybe be able to switch between two legs

0.25 wl

0.25 wl

25 Ft High

35 Ft High

20, 15, 10M

20, 15, 10M

17 and 12 M

17 and 12 M

• Or Switch between four legs (or three)

• Could be done as inverted vees with single center support

Dick Weber, K5IU

Aug 2, 2014

20M Horizontal Loops (Parallel to Ground) • Look at square, horizontal loop - 1/4 wl on a side / corner fed • Will compare to a horizontal loop with a 2:1 aspect ratio (maybe easier to put up in an attic space than a square loop) 0.34 wl 0.16 wl

0.25 wl

Don’t Feed Here

0.25 wl

25 Ft High 20, 15, 10M

17 and 12 M

35 Ft High 20, 15, 10M

25 Ft High 20, 15, 10M

35 Ft High 20, 15, 10M

17 and 12 M

17 and 12M

17 and 12M

Dick Weber, K5IU

Aug 2, 2014

20 M Loops (Perpendicular to Ground)

10M

• Look at feeding on vertical and horizontal side of loop • Delta loops not as good as square loops - lower leg may touch ground • Square Loop much better if at 35 ft and fed on horizontal leg

25 Ft High 20, 15, 10M

17 and 12M

35 Ft High 20, 15, 10M

17 and 12 M

25 Ft High

35 Ft High

20, 15, 10M

20, 15, 10M

17 and 12M

17 and 12M

Dick Weber, K5IU

Aug 2, 2014

20-10M W8JK Antenna of Inverted Vee Form at 25 and 35 Feet • • • •

20-10M multiband inverted vee form at 25 and 35 feet with 120 deg included angle 35 ft elements - 8 foot separation All plots at 20 deg elevation - patterns well behaved 20 to 10M Jan 1938 QST FYI - gains slightly higher if elements are fully horizontal 25 Ft High 20, 15, 10M

35 Ft High 20, 15, 10M

20M Free Space

17 and 12 M

17 and 12 M

10M Free Space

Dick Weber, K5IU

Aug 2, 2014

20-10M Comparison (1 of 2) Vpol Antennas

Hpol Antennas Inverted Vee

/ Moxon

Dipole

Horizontal 90 deg Bent Dipole

Hpol Vertical Square Loop

Horizontal Rectangular Loop

Horizontal Square Loop

Dick Weber, K5IU

Aug 2, 2014

20-10M Comparison 2 of 2 - Variants and Higher Gain Options

W8JK - Inverted Vee Form

Or build as parallel wires in attic 25ft 25ft

20M

12M

Quarter Wave Sloper

Dick Weber, K5IU

Aug 2, 2014

40-10M Antennas - Vpol - Hpol - Comparison

Dick Weber, K5IU

Aug 2, 2014

43 Ft Vertical Ground Mounted MFJ -2990 / Hy-Gain 6160

DX Eng 80VA-3

• 43 ft vertical exceeds 35 ft limitation shown for reference / information

• Would be susceptible to probable interaction with ground level obstructions

80M

20M -0.8

40M

30M

0.7

0.0

-1.3

10M

12M

17M

15M

-1.4

-0.5

Band Gain (dBi)

80 -1.3

0.6

40 -0.8

30 0.0

20 0.7

-6.4

17 -1.4

15 -0.5

12 10 0.6 -6.4

Dick Weber, K5IU

Aug 2, 2014

40M Verticals •

Concerns about ground mounted verticals: – Due to interactions from low obstacles (e.g. fences, shrubs) with high current portion of lower part of vertical element – Also extensive ground radial system needed to achieve good efficiency (>= 16 buried, symmetric radials)

•

Evaluate two versions with bases set at 6 feet – essentially self supporting or guyed with monofilament line – assume coils and matching is lossless / use ave ground Force 12 -Sigma Vertical Dipole HF Antennas for All Locations Moxon, G6XN 1983 p121

N6BT Bravo Vertical

Dick Weber, K5IU

Aug 2, 2014

40M Verticals Over Average Ground N6BT Bravo 40M Vertical 40

15

30 1 2 20

27 ft + 6ft = 33 ft 10 17

Force 12 -40M Sigma Vertical Dipole

40 15

24 ft + 6ft = 30 ft

30 1 2 20

HF Antennas for All Locations Moxon, G6XN 1983 p121

10 17

Dick Weber, K5IU

Aug 2, 2014

40M Sloping and Bent Dipoles on 40-10M “Forward”

Myth

35 ft

40

15

30

1 2

20 10 64 ft

17

“Forward” 40

15

35 ft

30 1 2 20 10

32 ft 17

Dick Weber, K5IU

Aug 2, 2014

40-10M Multiband Horizontal Antennas

Dick Weber, K5IU

Aug 2, 2014

40M Invert. Vee and Dipole at 25 and 35 Ft - Used Multiband • 40-10M multiband inverted vee at 25 and 35 feet with 120 deg included angle • All plots at 20 deg elevation ~ 70 Ft

~70 Ft

25 Ft High 40, 20, 15, 10M

30, 17, 12M

35 Ft High 40, 20, 15, 10M

30, 17, 12M

25 Ft High 40, 20, 15, 10M

30, 17, 12M

35 Ft High 40, 20, 15, 10M

30, 17, 12M

Dick Weber, K5IU

Aug 2, 2014

40M 1/2 wl Bent Dipole at 25 and 35 Ft - Used Multiband • 40-10M multiband, bent dipole - bent 90 degrees • Might be a potential choice to put in an attic space • Maybe be able to switch between two legs

0.25 wl

0.25 wl

25 Ft High

35 Ft High

40, 20, 15, 10M

40, 20, 15, 10M

30, 17, 12M

30, 17, 12M

• Or Switch between four legs or three

• Could be done as inverted vees with single center support

Dick Weber, K5IU

Aug 2, 2014

40M Horizontal Loops (Parallel to Ground) • Look at square, horizontal loop - 1/4 wl on a side / corner fed • Will compare to a horizontal loop with a 2:1 aspect ratio (maybe easier to put up in an attic space than a square loop) 0.34 wl 0.16 wl

0.25 wl

25 Ft High

0.25 wl

Don’t Feed Here

35 Ft High

25 Ft High

35 Ft High

40, 20, 15, 10M

40, 20, 15, 10M

40, 20, 15, 10M

40, 20, 15, 10M

30, 17 and 12 M

30, 17 and 12 M

30, 17 and 12 M

30, 17 and 12 M

Dick Weber, K5IU

Aug 2, 2014

40-10M W8JK Antenna of Inverted Vee Form at 25 and 35 Feet • 40-10M multiband invert vee form at 25 and 35 feet with 120 deg incl. angle • 70 ft elements - 16 foot separation • All plots at 20 deg elevation 25 Ft High

35 Ft High

25 Ft High

40

30

20

17

15

12

10

35 Ft High

Dick Weber, K5IU

40-10M Comparison 1 of 2

Aug 2, 2014 See Next Slide

Hpol Antennas

Vpol Antennas

Horizontal Rectangular Loop

Horizontal Square Loop

Horizontal Bent Dipole

Dick Weber, K5IU

Aug 2, 2014

40-10M Comparison 2 of 2 - Variants / Higher Gain Options 40, 20, 15, 10M

30, 17, 12M

W8JK - 70 ft Elements 16 ft Spacing

W8JK of Inverted Vee Form

Dick Weber, K5IU

Aug 2, 2014

End